I don't think that changes the fact that having debt != default. I have a mortgage for a multiple of my current income, that doesn't mean I'm bankrupt because

I don't think that changes the fact that having debt != default. I have a mortgage for a multiple of my current income, that doesn't mean I'm bankrupt because I'm unable to pay it off right now if demanded by the lender. Same thing with Social Security, if we had to suddenly pay out the entire amount tomorrow to everyone, yes we would be bankrupt but that's not how Social Security (or I would guess 90% or more of our debt securities) work.